Combustion Chamber Arrangement and System Comprising Said Arrangement

ABSTRACT

An object of the present invention is to provide a method and a system for implementing the method so as to alleviate the disadvantages of a reciprocating combustion engine and gas turbine when generating power. The invention is based on the idea of arranging a multifunction valve inside a combustion chamber to create more favourable favorable conditions for combustion process. The multifunction valve may act as an output valve, but it can also provide additional final compression to contents of the compression chamber and it may even capture part of energy released in a combustion process.

FIELD OF THE INVENTION

The present invention relates to a combustion chamber arrangement havinga multifunction valve, and to a power generating system comprising saidarrangement.

BACKGROUND OF THE INVENTION

In a gas turbine the first zone is exposed to temperature produced in acombustion chamber. Temperature of input gas to the gas turbinetherefore restricts efficiency of the gas turbine. In a piston enginecombustion is periodic which allows use of very high temperatures duringcombustion. However the reciprocating pistons and crank mechanismrestrict running speed of a piston engine as the pistons have a highmass and all the energy is converted into mechanical work of the pistonsand heat. In order to reach a decent efficiency, the pistons have to bewell sealed and lubricated.

A typical engine system of the prior art consists of a fuel tank and acombustion engine. An internal combustion engine comprises a set ofcylinders with a corresponding set of reciprocating pistons. One of theproblems associated with the above arrangement is that the movingpistons and other moving parts have to be constantly lubricated with oilwhich has a significant impact on running temperature of the combustionengine. Consecutively, the running temperature is a significant factorwhen considering the efficiency. The moving parts require constantlubrication and thus the above mentioned engine withstands runningtemperature of less than 100 degrees Celsius without a significantdeterioration of durability. Large portion of the produced heat is wasteheat which in relatively low temperature which in turn makes itdifficult to utilize the waste heat for energy production or otherpurposes.

U.S. Pat. No. 2,095,984 (H. Holzwarth) discloses an explosion turbineplant. The explosion turbine plant comprises an impulse rotor, pistonless explosion chambers for generating explosion gases and nozzles forexpanding and directing the gases to a rotor being driven exclusively byintermittent puffs of said gases.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is thus to provide a method and asystem for implementing the method so as to alleviate the abovedisadvantages. The objects of the invention are achieved by a combustionchamber arrangement and a system which are characterized by what isstated in the independent claims. The preferred embodiments of theinvention are disclosed in the dependent claims.

The invention is based on the idea of arranging a multifunction valveinside a combustion chamber to create more favourable conditions forcombustion process. The multifunction valve may act as an output valve,but it can also provide additional final compression to contents of thecombustion chamber and it may even capture part of energy released in acombustion process. The combustion chamber arrangement is locatedoutside a gas turbine and compressed air can be provided to thecombustion chamber in order to carry out a combustion process incontrolled and optimal conditions and use residue heat from the process.

An advantage of the arrangement and system of the invention is that themultifunction valve is used for delimiting a combustion zone within thecombustion chamber during input phase ensuring that a high pressure canbe achieved prior to ignition of fuel-air mixture in the combustionchamber. The combustion chamber arrangement also allows finalcompression to be made within the combustion chamber during whichpressure of the fuel-air mixture rises even further which in turnreduces need for raising the pressure with a compressor which would needmechanical energy. According to the present invention, heat is exhaustedfrom the system in relatively high temperature similar to a typical gasturbine. This high temperature exhaust creates favourable conditions forutilizing the exhaust heat.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail bymeans of preferred embodiments with reference to the attached drawings,in which

FIG. 1 illustrates a first electric generator system according to anembodiment of the invention;

FIG. 2 illustrates a second electric generator system with steamcirculation system according to an embodiment of the invention;

FIG. 3 illustrates a third electric generator system with an injector orejector system according to an embodiment of the invention;

FIG. 4 illustrates a detail of a system having two combustion chambers;

FIG. 5 illustrates the changes in pressure over time in a systemaccording to an embodiment;

FIG. 6 illustrates use of various available energy sources within thecombustion chamber according to an embodiment; and

FIGS. 7a to 7d illustrate a combustion chamber arrangement according toan embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to a simple example of FIG. 1, the power generator systemcomprises a turbine 22 which is in connection with a power shaft 51 anda compressor 24 axially or via a transmission 20. The system may alsocomprise an electric generator which can be driven with the power shaft51 or it may also be axially connected to the turbine 22. A rotor of theturbine 22 rotates when energy is fed to the turbine by means of fluidflowing through the turbine. Rotation of the turbine rotor drives thetransmission 20 and the power shaft 51 and the compressor 24 which bothare connected to the transmission. The turbine, the generator, the powershaft and the compressor may be connected to the transmission by meansof drive shafts, axles or other suitable power transmission means. Thearrangement converts the energy fed to the turbine 22 into mechanicalwork of the power shaft 51 and into air pressure with the compressor 24which compresses air for the combustion chamber 10. In an embodiment thecompressor 24 accumulates compressed air into an air tank 32 which thenfeeds the combustion chamber 10 with the compressed air accumulated inthe air tank 32. The compressor 24 is preferably a screw compressorwhich is highly efficient and able to provide high pressure to thecombustion chamber 10 and to the air tank 32. In an embodiment, thesystem comprises a second screw compressor connected in series with thefirst screw compressor 24 to provide even higher pressure to the airtank. In an embodiment, the system comprises a combination of an axialcompressor 24, such as a radial compressor and a screw compressorconnected in series with the axial compressor 24 to provide air to theair tank. One or more or all of the compressors can be for exampleaxial, radial, screw, piston or some other type of compressor. Theseries of compressors can be a combination of one or more of saidcompressor types connected in parallel or in series. The compressor orthe compressors are preferably arranged to build up pressure of over 2MPa to the air tank. In an embodiment, the compressor or the compressorsare arranged to build up pressure of over 3 MPa, 3.5 MPa or 4 MPa to theair tank. In an embodiment the compressor 24 may be driven with anelectric motor. In an embodiment an intercooler can be provided betweenthe series-connected first compressor and the second compressor to cooldown the air between the compressors. In an embodiment intercoolers canbe provided between some or all of the series-connected compressorstages to cool down the air between the compressors. The intercooler canthen be used to generate steam which can be injected into the combustionchamber in a form of short, high pressure steam pulses between expansionphases of the combustion cycle. In an embodiment serially connectedscrew compressors can share a common shaft so that successivecompression stages are partitioned along the common shaft andintercoolers are provided between each compression stages to extractheat from the compressed gas. Compressed air from any compression stagecan be directed to flow into a combustion chamber 10, air chamber 27,air tank 32 or some other part of the system.

The combustion inside the combustion chamber is deflagration combustion,not detonating combustion. Detonating combustion is an unwantedphenomenon as the pressure tends to rise to levels which can damage thesystem, especially controlled valves. Deflagration combustion isfundamentally different from detonation combustion which is unwanted inthe context of the present power generating system. Deflagration is asubsonic combustion process in which a flame front passes through afuel-air mixture with flame speeds from about one meter per second to afew hundred meters per second, releasing the heat of reaction at a slowpace. Detonation produces supersonic combustion wave that propagatesthousands of meters per second relative to an unburned fuel-air mixture.The detonation wave is a shock wave driven by the energy released inreaction zones right behind it.

The described systems are essentially based on Humphrey cycle engine.Main difference to Brayton cycle is that constant-pressure heat additionprocess of the Brayton cycle is replaced by a constant-volume heataddition process. Ideal Humphrey cycle consists of four processesreversible and adiabatic compression of incoming gas; constant-volumeheat addition; reversible and adiabatic expansion of the gas; andconstant-pressure heat rejection. In short, Humphrey cycle engine is adevice in which a significant part of compression and expansion of gasestakes place outside a combustion chamber in one or more steps. Saidsignificant part is preferably over 50% but in some embodiments it maybe over 20%, over 25%, over 30%, over 35%, over 40% or over 45%.

The electric generator system also comprises a combustion chamber 10which is arranged to receive compressed air from the compressor 24, airchamber or from the air tank 32 and fuel from a fuel tank 30 to initiatea combustion process. The compressed air is released from the air tankinto the combustion chamber 10 by means of a controllable multifunctionvalve. The compressed air is preheated before entering the combustionchamber with a heat recovery unit 40 which conveys heat from thecombustion chamber to the compressed air. A regenerator can be usedafter the last compressor to heat up the compressed air before it is fedto the combustion chamber or to a bypass duct which bypasses thecombustion chamber. The regenerator may use waste heat from e.g. exhaustgas or combustion chamber for heating up the compressed air. Thecompressed air may also be preheated with other means, for exampleelectrically with a resistor, when the system is started and thecombustion chamber is at room temperature.

In an embodiment one or more air chambers 27 each comprising a cylinderdefining a volume inside it and a movable piston for changing the volumeinside the cylinder, the volume being defined by the cylinder and thepiston. The cylinder comprises input and output for air and said inputand output are preferably controlled by one or more valves. The pistonpreferably comprises a valve, such as a clap valve or a flap valve, forenabling a flow of air in to the space defined by the cylinder and thepiston. The cylinder preferably comprises one or more air ducts on it orin its walls for heating or cooling the cylinder and its contents byrunning hot or cold air, respectively, through the one or more airducts. In this case hot air means hotter than the cylinder and cold airmeans colder than the cylinder. Compressed air from the compressor orfrom any stage of the serially connected compressors can be arranged toflow into the one or more air chambers. In an embodiment the systemcomprises one air chamber for each stage of serially connectedcompressors so that a flow of compressed air from each compressing stageis arranged to flow into a dedicated air chamber. In an embodiment theair pressure in a single air chamber can be raised gradually byarranging a flow of compressed air after each stage of seriallyconnected compressors to said air chamber.

The air chambers can be operated in steps which comprise cooling downthe air chamber, filling the air chamber gradually, heating up the airchamber and its contents, and finally, exhausting the compressed andheated air from the air chamber. The process repeats itself in a cyclehaving a certain cycle time. The heated air from the air chamber isexhausted preferably via heat exchanger to the combustion chamber. Theheat exchanger can be a part of the air chamber or in connection withthe air chamber. In an embodiment the air ducts of the cylinder of theair chamber form the heat exchanger.

The cooling step in the operation of the air chamber can be realized byarranging a flow of a fluid such as steam or ambient air or some othergas through the air chamber or through the air ducts of the air chamber.The cooling air can be in atmospheric pressure, i.e. approximately 100kPa. The cooling step may take for example 7.5% or 6 to 10% of the timeof the cycle, for example 9 seconds in a 120 second cycle or less in ashorter cycle.

In the filling step each air chamber is filled with air from dedicatedcompressing stage or in case of a single air chamber, it is graduallyfilled with air from one or more compressors until a desired pressurewithin the air chamber is reached. The input valve to the air chamber isopened and compressed air is arranged to flow into the air chamber. Thegradual filling is preferably achieved by arranging a flow of compressedair from more than one stage of serially connected compressors. Thedesired pressure may vary but it is higher than the atmosphericpressure. In an embodiment the desired pressure can be for example atleast 1.5 Mpa, 2 Mpa, 3 Mpa, 4 Mpa or some other pressure. The fillingstep may take far example less than 1% or 0.5 to 2% of the time of thecycle, for example 1 second in a 120 second cycle or less in a shortercycle.

The heating step is realized by arranging a flow of hot air, e.g. from aheat exchanger, through the air ducts of the air chamber. The heating ofthe air chamber and thus the air within the air chamber furtherincreases the pressure of the air within the air chamber. The heatingstep may take for example 40% or to 60% of the time of the cycle, forexample 50 seconds in a 120 second cycle or less in a shorter cycle.

In the exhausting step the output valve of the air chamber is opened andthe compressed and heated air is arranged to flow into the combustionchamber. Preferably the heated air flows through a heat exchanger 25before entering the combustion chamber. The exhausting of the compressedand heated air may be facilitated with the piston of the air chamber.The exhausting step may take for example 50% or 40 to 60% of the time ofthe cycle, for example 60 seconds in a 120 second cycle or less in ashorter cycle.

Fuel is released or pumped from the fuel tank and injected into the 10combustion chamber or mixed with air before introduction to thecombustion chamber. The fuel is preferably diesel or liquid natural gas(LNG). In an embodiment, the fuel is gasoline, natural gas, ethanol,biodiesel or a mixture of two or more the preceding fuels. In anembodiment, the fuel comprises hydrogen and carbon monoxide mixturewhich is a by-product of a soda recovery unit. In an embodiment water orsteam may be injected with fuel into the combustion chamber. In anembodiment the fuel comprises coal dust or brown coal dust as such ormixed to natural gas, diesel or some other suitable fuel.

The fuel injected into the combustion chamber ignites due to highpressure and temperature inside the combustion chamber or it is ignitedby a dedicated ignition system. The high pressure in the combustionchamber is arranged by releasing air from the air tank to the combustionchamber. In addition to the preheating, the heat of the combustionchamber heats up the released air inside the combustion chamber andbuilds up even higher pressure. The ignition may be continuouslytriggered by a dedicated energy source or when the system is started andthe combustion chamber has not yet reached its running temperature. Thededicated energy source for ignition can be e.g. an ignition coil, acondenser, a pre-combustion chamber, a glow plug, a pre-glowarrangement, a heater arrangement, plasma ignition and laser ignition.In an embodiment the system comprises an antechamber or a pre-combustionchamber. A fuel mixture can be ignited in the pre-combustion chamber toinitiate the combustion process. In multi-fuel systems, a mixture ofe.g., methane and air can be supplied to the combustion chamber and itcan be ignited with direct injection of diesel. The combustion processproduces heat which heats up the combustion chamber and keeps thecombustion process running by heating the fuel and the compressed airwhich are introduced into the combustion chamber. In an embodiment theignition is also used during the combustion cycle after the system isstarted. In an embodiment the heat recovery unit 40 or other means ofheat extraction is used to convey heat from the combustion chamber orcombustion process to water or steam and generate high pressure steam.The high pressure steam is injected into the combustion chamber betweenthe expansion phases of the combustion process. The steam is injected inshort, high pressure pulses and the amount of pulses between twoexpansion phases may be for example 1 to 10, 2 to 8, 3 to 6 or someother amount, such as 4, 5, 7 or 8.

In an embodiment the system comprises means, such as heat exchangers,for producing heat to a district heating system. Some of the thermalenergy that the electric generator system produces can be extracted fromthe system and transferred with heat exchanger to heating water of adistrict heating system. This combined production of electrical andthermal energy raises the overall efficiency of the system.

In an embodiment the system comprises means, such as heat exchangers,for using the thermal energy of the electric generator system to run anabsorption cooling system. Some of the thermal energy that the electricgenerator system produces can be extracted from the system andtransferred with heat exchanger to absorption cooling system which inareas of warm climate may raise the overall efficiency of the system.

The combustion chamber 10 is preferably a hollow container with inputmeans for fuel and compressed air and an output for combustion productsi.e. exhaust gas. The inputs and the output are controllable and may beclosed and opened in specific phases of a combustion cycle in order tobuild up pressure into the combustion chamber before the ignition of thefuel and to expel combustion products after the ignition. Input andoutput can be understood as an inlet and an outlet, respectively, butthe terms input and output are used throughout this text. One or morevalves can be used to control flow to and from the combustion chamber. Amultifunction valve 73, 74 is preferably used as an output valve butalso an additional output valve can be used. In an embodiment one ormore of the input valves are so called radial valves i.e. locatedradially around the combustion chamber cover. The input valves can befixed to an inclined position to the combustion chamber i.e. notperpendicular to the combustion chamber wall. In an embodiment one ormore input valves functionally connected to the combustion chamber 10for controlling the combustion process are fixed to an inclined positionto the normal of the combustion chamber wall so that an input of gasproduces a controlled whirl of gas to the combustion chamber. Theinclined position of a valve produces a whirl of gas in the combustionchamber when the gas is injected through the inclined valve. This typeof whirl can be controlled with the inclined valves whereas randomwhirls produced by perpendicularly positioned valves are very difficultif not impossible to control. The input valves can be used to controlthe whirl by selecting suitable inclination angles and/or by timingopenings of the valves. The combustion process in the combustion chamberis a cycle process which at least resembles Diesel cycle. Preheatedcompressed air from the air tank is introduced into the combustionchamber and fuel is injected into the combustion chamber until theair-fuel mixture ignites or is ignited. The combustion of the air-fuelmixture expands its volume so the combustion products and the compressedair are expelled through the output when the output valve is opened.Running speed of the combustion cycle is controlled by controlling theinput and output valves. The running speed may be chosen freely withincertain limits which are defined by the properties of the system. Suchproperties that may limit the running speed may be for example operationspeed of the valves, the air pressure in the air tank, 20 fuel type,etc. However, the running speed may be adjusted for optimal performancein each system because it is not restricted by moving pistons or similarphysical limitations of moving mass.

The combustion chamber has preferably a simple form at least in part ofthe combustion chamber, most preferably a cylinder form, for enabling aquick, dean and complete combustion process and simple design of themultifunction valve that is arranged to move within the combustionchamber. The simple form enables higher running temperatures whichincreases efficiency and decreases the amount of harmful particles andgases produced during the combustion process. The combustion chamber isarranged to function in high temperatures. In addition to the simpleform, also the material of the combustion chamber has to withstand hightemperatures without significant deterioration of performance ordurability. The material of the combustion chamber may be ceramic,metal, alloy or preferably a combination of two or more materials. Forexample, the combustion chamber may comprise an alloy encasing with aceramic inner coating. The alloy encasing withstands high pressure andstrong forces while the ceramic inner coating withstands high surfacetemperatures. The construction of the combustion chamber is preferablyarranged to withstand running temperature of 400 degrees of Celsius. Inan embodiment the combustion chamber is arranged to withstand runningtemperature of 500, 600, 700 or 800 degrees of Celsius or more. Thecombustion chamber itself does not comprise any moving parts so it isrelatively simple task to design the combustion chamber to withstandhigh temperatures. The moving parts that experience the highest thermalstress are the input valve(s) at the input of the combustion chamber andthe multifunction valve in the combustion chamber. The input valves arenot subjected to such high temperatures as they are cooled during eachinlet cycle by incoming air. However, there are valves readily availablethat are designed to operate in these temperatures and therefore itshould be relatively easy task to design and realize a durable inputvalve system. Operation of the multifunction valve is preferablydesigned so that the multifunctional valve has minimal necessaryexposure to the combustion. Also a cooling system can be arranged forthe multifunction valve.

FIGS. 7a to 7d illustrate a combustion chamber arrangement according toan advantageous embodiment of the invention. The combustion chamberarrangement can be used in embodiments of systems described within thisdocument. Terms combustion chamber, input valve and output valve in anyembodiment may refer to the combustion chamber arrangement. Thecombustion chamber arrangement comprises a combustion chamber 70 havingan input valve 71 for supplying e.g. fuel, air and/or steam in thecombustion chamber 70 and an output 72 for expelling combustion productsfrom the combustion chamber 70 into a turbine, for example. Furthermore,the combustion chamber 70 comprises a multifunction valve 73, 74. Themultifunction valve 73, 74 preferably comprises a valve disc 73 and astem 74 and it is preferably operated with a linear drive for moving thevalve disc 73 into various positions. The linear drive of themultifunction valve 73, 74 can be e.g. electric, pneumatic, hydraulic ormechanic.

The combustion chamber 70 may be formed of a hollow container having acenter axis X-X, a first axial end portion 70A, an opposite second axialend portion 70B, and an intermediate portion 70C between the first endportion 70A and the second end portion 70B. A first axial end of theintermediate portion 70C coincides with the first end portion 70A and asecond opposite end of the intermediate portion 70C coincides with thesecond end portion 70B. Air and/or fuel and/or steam may be supplied tothe first axial end portion 70A of the combustion chamber 70. The output72 of the combustion chamber 70 may be positioned in the second axialend portion 708 of the combustion chamber 70. The stem 74 is attached tothe valve disc 73 and protrudes out from the second axial end portion70B of the combustion chamber 70. The multifunction valve 73, 74 isaxially movable within the combustion chamber 70. The valve disc 73divides the interior of the combustion chamber 70 into two chamberportions at each axial side of the valve disc 73. The first chamberportion is formed between the valve disc 73 and the first axial endportion 70A of the combustion chamber 70. The second chamber portion isformed between the valve disc 73 and the second axial end portion 708 ofthe combustion chamber 70. The first chamber portion may form a variablevolume combustion chamber. The first chamber portion opens into theoutput 72 when the valve disc 73 moves towards the second axial endportion 708 of the combustion chamber 70. The output 72 is fully openwhen the valve disc 73 is in a retracted position at the second axialend portion 70B of the combustion chamber 70. The input valve 71 maydirect fuel, and/or air and/or steam in the axial direction X-X to thecombustion chamber 70. The output 72 expels the combustion products fromthe combustion chamber 70 in a radial direction i.e. in a directionperpendicular to the axial direction X-X. The output 72 is positioned ona radial outer surface of the second end portion of the combustionchamber 70. The outer perimeter of the valve disc 73 is at a smalldistance from the inner perimeter of the combustion chamber 70. There isthus no metal-to-metal contact between the outer perimeter of the valvedisc 73 and the inner perimeter of the combustion chamber 70. The stem74 may be hollow and the valve disc 73 may be provided with radialpassages for a medium e.g. steam. The medium may thus be suppliedthrough the stem 74 to the outer perimeter of the valve disc 73. Themedium may thus work as a seal between the valve disc 73 and thecombustion chamber 70. The surface of the valve disc 74 facing towardsthe first chamber portion may be solid. There is advantageously only asingle valve disc 73 within the combustion chamber 70.

The combustion chamber arrangement is divided in three zones forclarifying its operation. Combustion zone 81 is the topmost zone shownin FIG. 7b . The input valve 71 allows input to the combustion zone 81.FIG. 7c shows expansion zone 82 which is between combustion zone 81 andexhaust zone 83 shown in FIG. 7d . The output 72 is arranged from theexhaust zone 83. The multifunction valve is arranged to divide andcombine said zones. In topmost position of the multifunction valve, theexpansion zone 82 and the exhaust zone 83 are divided from thecombustion zone 81 by valve disc 73. In the middle position of themultifunction valve, the exhaust zone 83 is divided from combination ofthe combustion zone 81 and the expansion zone 82. In the lowest positionof the multifunction valve, the combustion zone 81, the expansion zone82 and the exhaust zone 83 form a continuous space within the combustionchamber 70. Thus, the multifunction valve comprises a valve disc 73 anda stem 74 mounted on the valve disc 73, wherein the valve disc 73 isarranged to be movable in the combustion chamber 70 for delimiting azone 81, 82, 83 or combination of zones within the combustion chamber70.

In an input phase of FIG. 7a input valve 71 is open for supplying e.g.fuel, air and/or steam in the combustion chamber 70. The multifunctionvalve is shown in middle position wherein the combustion zone 81 andexpansion zone 82 form a unitary space within the combustion chamber.Therefore the input fills both the combustion zone and the expansionzone. When input phase is completed, said space is filled withpressurized fuel, air and/or steam. Input valve 71 is closed and furtherrise in pressure can be achieved by moving the multifunction valve toits topmost position shown in FIG. 7b so that the valve acts as a pistonand compresses the input fuel mixture into the combustion zone. In otherwords, the multifunction valve is arranged to compress the inputcontents of the combustion chamber, such as fuel-air mixture, air or gasby reducing the volume of the delimited portion of the combustionchamber 70 when fuel and air has been supplied and the input valve 71 isclosed.

In an embodiment the multifunction valve is in topmost position duringthe input phase and therefore no additional compression can be achievedwith the multifunction valve,

In an embodiment the combustion chamber arrangement comprises acombustion chamber 70 for combusting fuel, an input valve 71 arranged tocontrol an input for supplying air, means for controlling an input forsupplying fuel into the combustion chamber, and an output 72 forexpelling combustion products from the combustion chamber 70. Thecombustion chamber arrangement further comprises a multifunction valvearranged to delimit a portion of said combustion chamber 70 to acombustion zone 81 and to hinder flow of fluids from said combustionzone 81 to the output 72 prior to ignition of fuel-air mixture, andarranged to remove said delimitation and to allow flow of fluids fromsaid combustion zone 81 to the output 72 after the ignition. Thus, anaspect of the invention is to provide a movable element between inputand output, delimiting the combustion chamber at the time of ignition inHumphrey cycle engine. In an embodiment said movable element, e.g. themultifunction valve, could also be e.g. pivotally connected to aconnecting rod arranged to rotate a crank shaft. Thereby converting partof the energy of the combustion process in to mechanical energy of thecrankshaft which can then be used to e.g. drive an electric generatorand convert the mechanical energy into electrical energy. The movableelement is arranged to move linearly by using an elongated stem, anextension of the stem or an extension rod between the movable elementand the connecting rod supported so that it moves linearly.

The input of fuel that is controlled can be realized with e.g. a directfuel injection system or an input valve. The input of fuel can also becontrolled with the same input valve that controls the input of air bysupplying fuel-air mixture as an input.

After the input phase the fuel-air mixture ignites or is ignited andcombustion of fuel mixture raises its temperature and pressure therebyexpanding it rapidly. During this combustion phase the multifunctionvalve is allowed to retract back to the middle position allowing thecombustion products to occupy expansion zone 82 in addition to thecombustion zone 81 where the combustion was initiated. Whenmultifunction valve is driven with electric linear drive, part of theenergy of said expansion of fuel mixture can be converted to electricenergy by using the electric linear drive as a generator during theexpansion phase. The electric linear drive of the multifunction valve isthus arranged to generate electricity when the valve disc 73 and stem 74are moved by an external force, i.e. a pressure difference over thevalve disc 73. Similarly, in cases of pneumatic, hydraulic andmechanical linear drives of the multifunction valve, the work done bythe multifunction valve can be converted into air pressure, hydraulicpressure and mechanical work. The described embodiment having themultifunction valve connected with the connecting rod to the crankshaftis an example of mechanical linear drive of the multifunction valve eventhough movement of the crankshaft is rotational. Ratio between energiesconverted with the linear drive and the turbine can be adjusted and itis preferably optimized for maximum overall efficiency of the system.

FIG. 7c illustrates the situation after retraction of the multifunctionvalve to the middle position. In order to reduce thermal stress to thevalve disc 73, the multifunction valve can be rapidly moved from middleposition to its lowest position thereby allowing the high pressurecombustion products to expand to the exhaust zone 83 and exit thecombustion chamber via output 72 into a turbine. One or more supportscan be used in the combustion chamber to reduce or eliminate possibleradial vibrations of the multifunction valve during movement between themiddle position and the lowest position of the multifunction valve. Inan embodiment volume of the exhaust zone 83 is minimized in ordermaximize the energy captured by the linear drive. The exhaust of thecombustion products from the combustion chamber can be facilitated byopening the input valve 71 and supplying steam or air in high pressurewhich will also cool down the combustion chamber and multifunctionvalve, and it also provides additional energy to the turbine,

The combustion chamber 70 has preferably an inside diameter slightlylarger than the valve disc 73 of the multifunction valve within theexpansion zone 82, i.e. between the topmost and middle positions of themultifunction valve, in order to prevent excess leaking between innerwall of the combustion chamber and the valve disc. It is advantageousduring input phase for increasing pressure within the combustion zoneand expansion zone. It is also advantageous during combustion phase andexpansion phase for maximizing the amount of energy that can beconverted to electricity with the electric drive of the multifunctionvalve. However, when moving the multifunction valve to its lowestposition, it can be beneficial that the combustion chamber has a largerdiameter in the exhaust zone 83 than in the expansion zone 82. Itfacilitates the exhaust through output 72 and it can also reduce thermalstress to the valve disc 73 of the multifunction valve. In the lowermostposition of the multifunction valve the valve disc 73 is preferablyaccommodated in a recess so that the valve disc receives only a minoramount of thermal energy from the exhaust flow of combustion products.

Sealing of a gap formed between the valve disc 73 of the multifunctionvalve and the inner wall of the combustion chamber 70 within theexpansion zone 82, i.e. between the topmost and middle positions of themultifunction valve, can be realized with various arrangements. In anembodiment no sealing is used and thereby a small leak of pressurethrough the gap is allowed. Any leak past the valve disc 73 eventuallyflows through the output 72 to the turbine. Thus minor leaking can betolerated in some cases. In an embodiment a ring gasket, e.g. a metalring gasket, is used for sealing the gap. In a preferred embodiment air,liquid water and/or steam is supplied through a duct to the valve disc73 and a flow of air, liquid water and/or steam is supplied through oneor more outputs in the valve disc 73 into the gap. Said duct ispreferably arranged within the stem 74 of the multifunction valve forenabling the flow of air or water, i.e. liquid water and/or steam, tothe valve disc 73 and from there to the gap. The flow of air, liquidwater and/or steam does not provide a perfect sealing but it has anadditional benefit of cooling the multifunction valve and the combustionchamber. In addition liquid water and/or steam lubricate the gap and ithelps to prevent direct contact between the valve disc and the innerwall of the combustion chamber thereby reducing mechanical wearing ofthem. In lowest position of the multifunction valve, the flow of air,liquid water and/or steam could be continued for cooling purposes andthe flow could be captured for recirculation using inputs and ductsarranged in the recess in which the valve disc is accommodated in thelowest position. In an embodiment the valve disc 73 comprises an inputand an output for cooling fluid and one or more ducts within the valvedisc running between said input and output. A cooling fluid circulationthrough the valve disc is arranged in the lowest position of themultifunction valve for cooling the valve disc before each input phase.

A system comprising said combustion chamber valve preferably comprisesmultiple pressure, temperature and/or mass flow sensors for controllingthe linear drive of the multifunction valve for changing the position ofthe multifunction valve. The controlling of the linear drive of themultifunction valve can be based on measuring data of suction side massair flow sensor, pressure sensor and/or temperature sensor; fuel massflow sensor; pressure sensor and/or temperature sensor in combustionchamber, prior to a turbine or after a turbine; temperature sensorand/or mass flow sensor in heat recovery unit; mass flow sensor,temperature sensor or pressure sensor of input water and/or steam; andlambda sensor. The controlling can be based on measurements of one ormore of said sensors.

The output of the combustion chamber leads a stream consisting of thecombustion products and the compressed air from the combustion chamberinto the turbine 22. Due to the high pressure in the combustion chamber,the stream is expelled with high velocity when the output is opened. Theexpelling of the combustion products may be enhanced by having theoutput and the air input open simultaneously for a certain period oftime The turbine 22 comprises a rotor which rotates when the streamflows through the turbine. The rotating rotor drives the transmission 20which in turn drives the power shaft 51 and the compressor 24 as statedearlier. The stream is guided to exhaust pipe 90 after the turbine andthe exhaust gas 98 is released from the system. The power shaft 51provides the output of the system and it can be connected to e.g. adrivetrain of a vehicle or an electric generator for converting themechanical work into electric energy.

The combustion chamber 10, 70 is preferably a separate unit outside theturbine 22. The combustion products expelled from the combustion chamber10 are guided to the turbine 22 with a pipe, tube or some other channelconnecting the combustion chamber 10, 70 and the turbine 22. In anembodiment the system comprises multiple combustion chambers. In thatcase each combustion chamber has a pipe, tube or some other channelconnecting that combustion chamber to the turbine 22. Preferably themultiple combustion chambers are arranged to expel their combustionproducts sequentially, i.e. not all at the same time, to provide asteadier flow of combustion products to the turbine 22. In anembodiment, the steadier flow to turbine 22 is accomplished with short,high pressure steam pulses which are injected into the combustionchamber between the expansion phases of the combustion process. In anembodiment two or more combustion chambers are arranged to expel theircombustion products simultaneously in order to produce a high peak ofenergy to the turbine.

In an embodiment a generator driven by the power shaft 51 feeds anelectric storage system which comprises one or more capacitors, supercapacitors or batteries for storing the electrical energy produced bythe generator. This type of system can be used in vehicular applicationsfor producing and storing electrical energy for electrical motors of avehicle. Also in vehicular applications the system can comprise anadditional air tank or it may be connected to an air tank of the vehicleusing it as a hybrid air tank for two purposes. The additional air tankmay be filled with compressed air from a compressor of the electricgenerator system or a compressor of the vehicle. Energy from braking ofthe vehicle can be converted in to compressed air with the compressor ofthe vehicle and stored in to the additional air tank. The vehicle mayalso comprise an exhaust brake which can also be connected to theadditional air tank for increasing the pressure of the additional airtank. The compressed air of the additional air tank can be supplied tothe compressors of the electric generator system where the pressure ofthe air is increased to final desired level.

Now referring to FIG. 2, in an embodiment the power generator systemfurther comprises a generator 26 driven by the power shaft and a steamcirculation system. The power generator system having a generator iscalled an electric generator system. The steam circulation systemcomprises a steam tank 34, a heat recovery unit 40, a heat exchanger 42,a condenser 50 and a water tank 36. In an embodiment, the steamcirculation system further comprises a second turbine. Water and steamcirculates in the steam circulation system wherein the water isaccumulated into the water tank 36 and the steam is accumulated into thesteam tank 34. In an embodiment the steam tank and the water tank is asingle tank wherein the water is accumulated in the bottom of the tankand steam is accumulated on the top of the tank. The flowing of thesteam is based on pressure differences within the system but it might beassisted with pumps or similar arrangement if necessary. The flowing iscontrolled by means of a number of valves which may be operated incontrolled manner.

The steam is arranged to flow from the steam tank 34 to the heatrecovery unit 40. The heat recovery unit 40 is in thermal connectionwith the combustion chamber 10, 70 so that the combustion chamber heatsup the heat recovery unit in which the heat is conveyed to the steamflowing through the heat recovery unit. The heat recovery unit may be aseparate unit having a thermal connection to the combustion chamber orit may be a fixed part of the combustion chamber. In an embodiment theheat recovery unit may even a pipework inside the combustion chamber ortubing on the surface of the combustion chamber. When the heat from thecombustion chamber is conveyed to the steam flowing through the heatrecovery unit, the steam rapidly heats up and expands. The steam flow isthen directed to the turbine 22 wherein the steam flow rotates the rotorof the turbine 22 simultaneously with the combustion products andcompressed air which are expelled from the combustion chamber 10, 70into the turbine 22.

In an embodiment a heat pump can be used to produce steam. Heat pumpsare known to be effective when needed temperature difference is small. Aheat pump is therefore a good alternative for adding thermal energy towater which is at or near its boiling point. For example an air-to-wateror water-to-water heat pump can be used for producing steam from waterthat is preheated to near or at its boiling point. The steam productioncan be assisted with other energy sources, including those alreadymentioned, in addition to the heat pump. In an embodiment steam ofexhaust flow is condensed into water and the heat released from thecondensing is used as a heat source for the heat pump. The temperaturewhere the condensing takes place depends on the pressure of the exhaustgas and steam. Said temperature is 100 degrees Celsius in atmosphericpressure but in higher pressure it can be for example as high as 200,300, 400 or even 500 degrees Celsius. The heat pump uses the heat tovaporize water for providing fresh steam to the system. In an embodimentheat provided by one or more intercoolers of the system is used as aheat source for the heat pump.

In an embodiment the heat recovery unit 40 is replaced with heatinsulating material and time-dependent steam injections to thecombustion chamber 10, 70 maintain a stable running temperature of thecombustion chamber. The time-dependent steam injections are preferablyshort, high pressure steam pulses injected into the combustion chamberbetween expansion phases of the combustion process. The injected highpressure steam pulses need only a reduced amount of steam due to theirshort pulse type length. After injection the steam exits the combustionchamber and enters into the turbine 22.

In an embodiment the system comprises an additional burner forincreasing the amount and/or the temperature of the steam in the system.The burner preferably uses the same type of fuel as the rest of thesystem. The fuel is burned in the burner for producing heat which thenheats steam and/or the burning fuel heats water to produce steam. Theadditional burner can be used in systems which do not produce enough“waste heat” to produce an adequate amount of steam. The system is alsoadapted to use other external heat sources and thus heat as such orconverted into compressed air or steam can be input to the system fromexternal sources. The external source can use the same fuel or adifferent fuel than the combustion chamber of the system. Examples ofusable heat energy from external sources can be e,g. waste heat of aheavy machine process, waste heat of a vehicle's engine or brake system,geothermal energy, etc. In an embodiment where the system producesexcess heat, a portion of the heat produced by the system can beconverted in an external process e.g. In Rankine process or Stirlingprocess to mechanical work. The use of the additional burner ensuresthat a desired amount of steam in a desired temperature and pressure canbe achieved.

In an embodiment, the steam is not directed into the same turbine 22 asthe combustion products. In that embodiment the system comprises asecond turbine which is dedicated to the steam stream while the (first)turbine 22 is dedicated to the stream of combustion products andcompressed air. The stream of combustion products and compressed air mayeven be arranged to flow through an additional heat exchanger after theturbine 22 to heat up the steam stream before that stream enters thesecond turbine. The arrangement of the second turbine may be similar toknown combined cycle power plants.

From the turbine a stream of steam, compressed air and combustionproducts flows through the heat exchanger 42 to the condenser 50 whereinthe steam is condensed into water and the compressed air and thecombustion products are guided out of the system through exhaust pipe90. In the embodiment of the second turbine the stream of combustionproducts and compressed air is arranged to flow through heat exchanger42 directly to exhaust pipe and the steam stream is arranged to flowthrough the heat exchanger 42 and the condenser 50 to the water tank 36.

Condensing water from the exhaust flow may cause accumulation ofimpurities to the system which is undesirable. In an embodiment this issolved by feeding the condenser with fresh, atmospheric air from whichrelatively clean water can be condensed to the system.

The water condensed from the steam and/or from the atmospheric air flowsinto the water tank 36 or is pumped in there. An ion exchanger 52 may bearranged between the condenser 50 and the water tank 36 for purifyingthe water before it enters the cycle again. The water tank 36accumulates water which is then guided or pumped to the heat exchanger42. The heat exchanger conveys the heat from the stream of steam,compressed air and combustion products to the water flowing through theheat exchanger. The heat of the heat exchanger vaporizes the water intosteam which is then guided to flow back into the steam tank 34. From thesteam tank 34 the high pressure steam can be released in short bursts tocreate short, high pressure pulses to the combustion chamber.

FIG. 3 illustrates an electric generator system which is otherwisesimilar to the system of FIG. 2 except that the system further comprisesa pump having a converging-diverging nozzle, for example an injector orejector 12 for combining the stream of combustion products from thecombustion chamber 10, 70 and the steam from the heat recovery unit 40or from the heat exchanger 42 wherein the ejector 12 guides the steamand combustion products into the turbine 22 for rotating the rotor ofthe turbine. The pump having a converging-diverging nozzle is called anejector within the description but in an embodiment the pump can also befor example an injector, steam injector or steam ejector. The ejector 12is between the turbine and the combustion chamber and its heat recoveryunit. The combustion products and the compressed air are expelled intothe ejector wherein the steam from the heat recovery unit is superheatedby the hot matter from the combustion chamber. The superheating of thesteam causes rapid expansion of the steam. The ejector 12 guides thestream of superheated steam, combustion products and compressed air intothe turbine 22 wherein the stream rotates the rotor of the turbine. Inan embodiment, short, high pressure steam pulses are injected into theejector 12 from where the steam flows to the turbine and rotates therotor or the turbine. In an embodiment an afterburner can be used in theejector 12 between the combustion chamber 10 and the turbine 22.However, the temperature of the exhaust gas has to be monitored andcontrolled since the input gas of the turbine should preferably have alow temperature and the afterburner rises the temperature of the exhaustgas. In an embodiment the afterburner is used intermittently and notcontinuously.

In an embodiment the system also comprises an adjustable nozzle and avalve in connection with the ejector 12 and the output of the combustionchamber 10, 70 for adjusting the expelling of combustion products fromthe combustion chamber 10, 70. The nozzle has a certain design and aform which may be altered. The nozzle is within the ejector in a by-passflow of the steam flowing from the heat recovery unit 40 to the turbine22. The form of the nozzle has a significant impact to the expelling ofthe combustion products from the combustion chamber when the valve inthe output is open. By altering the form of the nozzle the expelling ofthe combustion products may be increased with help of the by-pass flowof the steam.

In an embodiment a portion of the combustion products, i.e. the exhaustgas, is guided to a low temperature/pressure region of the turbine 22 orto a low pressure turbine when the exhaust gas is exhaust from thecombustion chamber. An ejector or ejectors 14 a, 14 b can be omitted inthis embodiment since the pressure in suction side is higher than thepressure in low temperature/pressure region.

FIG. 4 illustrates a detail of an embodiment of a combustion systemhaving two combustion chambers 10 a and 10 b and an ejector 12. Thenumber of combustion chambers and ejectors is not limited to thisexample. Two combustion chambers and one ejector were chosen for thisembodiment to give an example and represent the capabilities of thesystem. In an embodiment the electric combustion system has one, two,three, four or more combustion chambers and zero, one, two, three, fouror more ejectors. In an embodiment the ejectors are not essential andthe system can operate without a single ejector.

Each combustion chamber 10 a, 10 b comprises one or more inputs 101, 102which can be controlled with or without input valves and one or moreoutputs 111, 112 which can be open or controlled with output valves. Theinputs and the outputs may be controlled without valves by controllingthe 15 pressure of the inputs and outputs because gases tend to flowfrom a higher pressure region to a lower pressure region. In anembodiment at least some of the inputs and outputs are controlled withgas vibrations or oscillations instead of valves. Movement of gas in apipeline tends to oscillate with a frequency or a plurality offrequencies which is/are specific to the pipeline and the gas, so calledeigenfrequencies. The pulse action is created by the periodic combustionand fortified by the eigenfrequencies of the flow system. Specificoscillation frequencies can be exploited by controlling the periodiccombustion process to match the frequency of the specific gasoscillation so that these amplify each other. In an embodiment thecombustion cycle is matched with the specific oscillation frequency ofthe compressed air flowing in the system. In an embodiment valveactuation is optimized to harmonize with the desired periodicaloperation of the pulse turbine. In an embodiment the combustion cycle,the specific oscillation frequency of the compressed air flowing in thesystem and a specific oscillation frequency of the steam flowing in thesystem are all matched to the same phase so that they amplify eachother. The specific oscillation frequencies of the steam and thecompressed air flows can be matched with pipeline design. In anembodiment the combustion cycle is matched with the specific oscillationfrequency of the compressed air flowing in the system and with thespecific oscillation frequency of the steam flowing in the system butthe specific frequencies of the steam and the compressed air are notmatched with each other. Preferably the flow system is optimized suchthat the flow losses are minimized.

In an embodiment the system comprises compressors connected in series toproduce high pressure compressed air to the combustion chamber. Atypical way is to feed compressed air from the first compressor to thesecond compressor and from the second compressor to the thirdcompressor, and so on. The pressure of the compressed air builds up ineach compressor stage and finally the compressed air from the lastcompressor of the series of compressors is released to the combustionchamber or to the air chamber. This is energy consuming as the amount(mass) of compressed air is the same in each compressing stage. Acompressing stage can be a single compressor or a number of compressorsin parallel connection i.e. each having common input and output. In anembodiment serially connected screw compressors can share a common shaftso that successive compression stages are partitioned along the commonshaft and intercoolers are provided between each compression stages toextract heat from the compressed gas. Compressed air from anycompression stage can be directed to flow into a combustion chamber 10,70, air chamber, air tank 32 or some other part of the system. In anembodiment a portion of the mass of the compressed air is released tothe combustion chamber and the remaining portion of the mass of thecompressed air is released to the following compressor in the series ofcompressors. The pressure within the combustion chamber rises graduallyas the compressed air is released to the combustion chamber betweencompressing stages. Heat can be extracted from the compressed airbetween the compressing stages by using one or more intercoolers. Alsothe amount of air to be compressed diminishes in subsequent compressingstages as part of the air is released to the combustion chamber betweenthe compressing stages. A plurality of pressure tanks can be used forstoring compressed air in various pressures between atmospheric pressureand the highest pressure from the last compressor. A further advantageis that the gradual air feeding allows the other inputs to be fed to thecombustion chamber during a desired pressure. For example the combustionchamber could first receive a first release of compressed air, then afuel input, then a second release of compressed air, then a steam inputand finally a third release of compressed air to a desired finalpressure. The order and timing of the inputs can be optimized based onthe system variables.

In an embodiment the combustion chamber is arranged to work in twoalternating cycles. The first cycle may be any of the combustion cycles,i.e. a topping cycle, where fuel is fed to the combustion chamber asdescribed within this document. The second cycle is a cooling cycle,i.e. a bottoming cycle, wherein the combustion chamber is cooled bymeans of arranging a flow of fluid, such as ambient air, steam or someother gas, through the combustion chamber. Cooling the combustionchamber transfers thermal energy from the combustion chamber to thefluid flowing through the combustion chamber and thus makes thecombustion chamber less warm. Both cycles may take an equal amount oftime. In an embodiment the first cycle is longer than the second cycleor the first cycle is shorter than the second cycle.

FIG. 6 illustrates an embodiment wherein the combustion chamber isarranged to work with various available energy sources in order toachieve a desired effect. Typical desired effects include fuel economyand temperature control and power control. For example, the turbine hasa temperature limit for input gas to protect the turbine but typicallyhigher combustion temperatures give better fuel economy. The turbineinput temperature limits the efficiency of the system when thecombustion chamber operates only with high temperature topping cycles. Avast supply of compressed air or steam from e.g. waste heat or externalsources enables use of higher combustion temperatures and pressures intopping cycles when the available air or steam can be used in bottomingcycles after topping cycles to lower the average input gas temperatureto the turbine. In FIG. 6 solid line illustrates pressure achieved withcombustion of fuel in topping cycle and dotted line illustrates pressureachieved with input of compressed air or steam to the combustion chamberin bottoming cycle. Cycles t_(c1) and t_(c5) are topping cycles in whichfuel is combusted and t_(c2), t_(c3), t_(c4) and t_(c6) are bottomingcycles in which fuel is not combusted. In t_(c1) the combustion of fuelis supplemented with short injections of compressed gas or steam afterignition of fuel. This enables use of higher temperatures in toppingcycles and therefore results higher efficiency and better fuel economy.If an external source generates plenty of heat which is converted intosteam, the system can be run with the steam for extended periods of timewithout using any fuel during that period. Preferably the availableenergy from different sources is constantly monitored with sensors anddecision between topping cycle and bottoming cycle is preferably madeeach time based on e,g. available energy sources and required power. Thetopping and bottoming cycles can be used simultaneously, with a phasedifference to each other, in alternating order or following a pattern,This can be achieved with control hardware and software well known inthe art by programming the control system to follow these rules andconditions.

In an embodiment each combustion chamber comprises an output controlledby a main exhaust valve 111. In an embodiment each combustion chambercomprises two outputs, one output being controlled by a main exhaustvalve 111 and one output being controlled by an auxiliary exhaust valve112. In an embodiment each combustion chamber comprises an open outputwhich is not controlled by valve. In an embodiment each combustionchamber comprises an input 101 for fuel. In an embodiment eachcombustion chamber comprises inputs 101, 102 for fuel and pressurizedair. In an embodiment each combustion chamber comprises inputs for fuel,pressurized air and steam. In an embodiment each combustion chambercomprises inputs for one or more of the following: fuel, pressurizedair, steam and water. The steam may be produced at least partially usingwaste heat of the combustion process of the system. In an embodiment,the steam is injected in the form of short, high pressure steam pulseswhich are injected into the combustion chamber between the expansionphases of the combustion process. In this embodiment, the exhaust valvesmay be omitted as the pressure and temperature conditions of thecombustion chamber are controlled with the steam pulse injections. In anembodiment steam is injected into combustion chamber and/or to theejector 12 and to the turbine 22. When both combustion chambers outputsare closed, steam can be injected directly into the ejector 12. In anembodiment, an ORC turbine or a Stirling engine can be used after theheat exchanger for cooling the exhaust gas and steam in a temperaturerange of about 200 degrees Celsius,

A combustion cycle in the system of FIG. 4 could have the followingsteps, First pressurized air is fed to the combustion chambers 10 a, 10b via air inputs 102 and fuel is fed to the combustion chambers 10 a, 10b via fuel inputs 101. In an embodiment fuels, especially gaseous fuels,can be compressed prior to feeding them into the combustion chamber.Fuels like for example carbon monoxide or hydrogen can be fed in apressure higher than atmospheric pressure to the combustion chamber. Thepressure in the combustion chambers is built up due to residue heat andpossibly with multifunction valve until the fuel in the combustionchambers ignites, for example at 2 to 3 MPa pressure, and producescombustion products and more pressure. The multifunction valve is movedto its lowest position and the combustion products and the pressure arereleased to the ejector 12 by opening the main exhaust valve 111 betweena combustion chamber 10 a and the ejector 12. In an embodiment the mainexhaust valve is omitted and the combustion products move freely to theejector 12 after the multifunction valve is moved to its lowestposition. In an embodiment a pressure wave supercharger replaces themain exhaust valve. Preferably the combustion cycles in each combustionchamber runs with a phase difference to the other combustion chambers sothat the exhaust stream from the combustion chambers is steadier andless pulse-like. The combustion products flow from the combustionchamber to the ejector 12 and from ejector to turbine 22 through anoutput 113. At the same time, liquid water and/or water vapour i.e.steam can be injected to the combustion chamber 10 a via inputs and/ormultifunction valve, thus improving the ventilation of the combustionproducts out of the combustion chamber. Preferably steam is injectedinto the combustion chamber in short pulses with high steam pressure,for example ranging from several MPa to ten Mpa. The injection of steamalso helps to keep the pressure in an elevated level for an extendedperiod of time as can be seen from FIG. 5. The injection of water and/orsteam also lowers the temperature of the combustion chamber andfacilitates temperature controlling. The combustion chamber may haveducts formed within combustion chamber cover for water and/or steamcirculation on exhaust side of the combustion chamber. One or more ofthe ducts of the combustion chamber may be connected to ducts of themultifunction valve. The water and/or steam can be injected into theducts which water and/or steam then perspirates from small apertures ofthe ducts. Heat is transferred from the exhaust side of the combustionchamber to the perspirating injected water and/or steam and thecombustion chamber cools down. In an embodiment similar ducts andcooling system is used on the main exhaust valve. The injection lowersthe temperature of the main exhaust valve 111 which can extend thelifetime of the main exhaust valve 111. When the pressure in thecombustion chamber and in the ejector has dropped, for example to 4 to 5MPa, the main exhaust valve 111 is closed. One or more of the valves maybe electronically controlled for example via a control unit. In anembodiment the main exhaust valve 111 can be omitted when steam pulsesare injected into the combustion chamber so the main exhaust output iscontrolled solely with the multifunction valve.

In an embodiment including the main exhaust valve, after closing themain exhaust valve 111 the ejector can be sprayed with liquid waterand/or water vapour i.e. steam via valve 103 which raise the pressure inthe ejector 12, for example to 6.5 MPa. At a certain pressure in theejector 12, for example 6.5 MPa, the main exhaust valve 111 of thesecond combustion chamber 10 b opens and releases combustion products tothe ejector 12 and from there to the turbine 22. At the same time thesecondary exhaust valve 112 of the first combustion chamber 10 a is keptopen to ventilate the residue combustion products from the firstcombustion chamber 10 a. The ventilation can be enhanced by introducingpressurized air or steam via the inputs 101, 102 to the combustionchamber. The secondary exhaust valve 112 may lead the residue combustionproducts to the turbine 22 via one or more second ejectors 14 a, 14 b.In an embodiment steam is injected into combustion chamber and/or to theejector 12 and to the turbine 22. When both combustion chambers outputsare closed, steam can be injected directly into the ejector 12. In anembodiment a single second ejector can comprise multiple inputs so thatit can be used with two combustion chambers. Once the first combustionchamber 10 a is ventilated and the pressure has dropped to asufficiently low level, for example to 2, 1, 0.5 or 0.2 MPa, thesecondary exhaust valve 112 is closed and the next cycle of thecombustion cycle can begin.

In an embodiment the second ejector 14 a, 14 b is arranged to receivemotive steam or motive gas via input 114. The motive gas is preferablypressurized water vapour for example in 6, 8 or 10 MPa pressure. Themotive gas is directed through the second ejector 14 a, 14 b anddischarged to the ejector 12 via valve 104. When the motive gas goesthrough the second ejector it creates a suction effect drawing residuecombustion products from a combustion chamber 10 a, 10 b when outputvalve 112 connecting the combustion chamber to the second ejector isopen. The valve 104 is preferably a control valve. The throughput and/oropening direction of the valve 104 can be adjusted. In an embodiment allexcess steam produced within the system can be fed to the turbine viathe valve 104 and/or the second ejector 14 a, 14 b.

In an embodiment a back flow from the turbine 22 using an intermediatesteam tapping can be introduced to a third ejector. The back flow or theintermediate steam from the turbine may comprise steam or combustionproducts or a mixture of steam and combustion products which areintroduce to the third ejector. The pressure of the intermediate steamat the third ejector is raised to a sufficient level by using valves andintroducing gas such as water vapour to the third ejector. The steam andthe combustion products increase the volume of the gas and decrease thetemperature of the gas. The mixture of gases is introduced from thethird ejector to the ejector 12 for example via the second ejector 14 a,14 b and valve 104, or to some other input valve of the system. In anembodiment, an output using an intermediate steam tapping can also beintroduced right after the heat exchanger.

In an embodiment the turbine is arranged to rotate a by-pass fan in anaviation application for example replacing turbofan engines ofcommercial airplanes. In an embodiment the system comprises an oxygentank connected to the combustion chamber and controlled with a valve.The combustion chamber can be used as a combustion chamber of rocketengine using rocket fuel from the fuel tank and oxygen from theatmosphere in the lower atmosphere so that the oxygen from the oxygentank can be used in the upper atmosphere where the amount of oxygen isnot sufficient for the combustion.

FIG. 5 illustrates time dependence of pressure in a system according toan embodiment. As the combustion cycle causes the pressure to changewithin the system in rather broad range, the turbine 22 does not receiveoptimal input unless the system in controlled in a time-dependentmanner. Preferably all the inputs 101, 102, 103, 104 are controlled intime-dependent manner to keep the output 113 to the turbine in optimalpressure. Without any other time-dependent inputs than fuel and air, theoutput to the turbine would look like the curve 200 in FIG. 5. In thebeginning of the combustion cycle the pressure builds up quickly peakingjust before the main exhaust valve 111 is opened or the multifunctionvalve is moved to its lowest position in absence of the main exhaustvalve, which quickly lowers the pressure as the combustion products flowthrough the turbine. Now if the combustion chamber is injected withliquid water and/or water vapour immediately after the main exhaustvalve 111 or the multifunction valve is opened, the pressure would notfall as quickly because the liquid water would evaporate and the vapourwould heat up due to residue heat of the combustion chamber and thus theinjection would lessen the impact of opening the main exhaust valve 111or the multifunction valve. In a similar manner, once the main exhaustvalve 111 or the multifunction valve has been closed, the ejector can besprayed with liquid water and/or water vapour i.e. steam via valve 103which raise the pressure in the ejector 12 thus raising the outputpressure to the turbine. The amount of liquid water, steam and air iscontrolled in a time-dependent manner in order to prevent the output tothe turbine from dropping too much. Keeping the output to the turbine inan elevated and relatively constant level has a significant impact onthe efficiency of the system. The turbine can be driven in optimaloperating range most of the time with a relatively constant outputwhereas the turbine can not make the most out of sparse, short bursts.

The output to the turbine can be maintained in an elevated level withthe injection of water, steam and air. This elevated level isillustrated with dashed line 201 in FIG. 5. However, a lot of steam andair is needed to maintain such a high pressure if the main exhaust valveis omitted or kept constantly open. If the injection of steam is in theform of very short and high pressure pulses, the main exhaust valve canbe omitted thus simplifying the system and increasing its reliability.Curve 202 represents the pressure level during a combustion cycle whenthe injections are in the form of short steam pulses. The short steampulses can maintain the average pressure at a high enough level that themain exhaust valve is not necessary. The short steam pulses may havepeak pressure higher than the pressure pulse caused by the combustion.In an embodiment of e.g. two combustion chambers, short steam pulses canbe fed to the system (e.g. to the first combustion chamber) after fuelis ignited and combustion products expelled from the first combustionchamber. The feeding of steam pulses can be continued while an exhaustvalve of the second combustion chamber is closed. During that time anyresidue steam and combustion products are flushed from the secondcombustion chamber. The second combustion chamber is flushed with aninput of compressed air which flows through e.g, a secondary exhaustvalve 112 which then conveys the air and the residues to e.g. lowerpressure turbine. After the flushing the second combustion chamber isfilled with compressed air, fuel is injected to the second combustionchamber and the mixture ignites or is ignited. After the fuel is ignitedand combustion products expelled from the second combustion chamber,short steam pulses can be fed to the system (e.g. to the secondcombustion chamber) while the exhaust valve or the multifunction valveof the first combustion chamber is closed, the first combustion chamberis flushed, filled and ignited like the second combustion chamberearlier, and so on. This enables high enough pressure for efficient useof the turbine throughout the process.

In an embodiment the pressure within the ejector 12 is kept always overfor example 2, 3, 4 or 5 MPa. In an embodiment the amount of injectedwater, steam and air and point of time at which those are injected aredetermined based on measured quantities of the system. Such measuredquantities can be for example temperature, pressure, humidity, gascomposition, state of a valve or some other process quantity. Saidquantities can be measured with e.g. sensors. In an embodiment theamount of injected water, steam and air and point of time at which thoseare injected are determined based on the phase of the combustion cycle.The time dependent injection of water, steam also increases thereliability of the turbine 22 by controlling the temperature of the gaswhich is introduced to the turbine 22. The injection of water and steamlowers the average temperature of the gas introduced to the turbine andtherefore it allows for higher pressure (and thus higher temperature) tobe used in the combustion chamber.

In an embodiment the power generator system is used together with aturbocharged combustion engine. The power generator system can feedsupplemental energy to the turbocharger of the combustion engine whichcan be beneficial in three ways. First, the pressure ratio of theturbocharger can be controlled regardless of running speed (rpm) and/orload of the combustion engine. This is beneficial in controllingemissions and pollutants of the combustion engine and it also improvesload response of the combustion engine. Also the compressor belonging tothe pulse turbine system can be used for supplying the input of air.Second, the system may provide output of mechanical power from a shaftof the turbocharger or the turbine of the power generator system whichprovides an additional power which depends on the amount of additionalenergy fed to the system. Third, the power generator system can use atleast part of the exhaust flow of the combustion engine s an energysource. Also the input of air to the combustion chamber can be arrangedwith air supply system of the combustion engine as such or supplementedwith additional air supply pump, such as Roots Hower. Also a compressorof the power generator system can be used for supplying the input ofair.

It will be obvious to a person skilled in the art that, as thetechnology advances, the inventive concept can be implemented in variousways. The invention and its embodiments are not limited to the examplesdescribed above but may vary within the scope of the claims.

1. A combustion chamber arrangement comprising a combustion chamber forcombusting fuel, an air input valve arranged to control an input forsupplying air, a controllable input for supplying fuel to the combustionchamber, and an output for expelling combustion products from thecombustion chamber, the combustion chamber being formed of a hollowcontainer having a center axis, a first axial end portion and anopposite second axial end portion, wherein the air and the fuel aresupplied to the first axial end portion (70A) of the combustion chamber,the output is positioned in the second axial end portion of thecombustion chamber, and the arrangement further comprises amultifunction valve axially movable within the combustion chamber, themultifunction valve comprising a valve disc and a stem mounted on thevalve disc and protruding out from the second axial end portion of thecombustion chamber, whereby the valve disc divides the interior of thecombustion chamber into two chamber portions at each axial side of thevalve disc, the first chamber portion formed between the valve disc andthe first axial end portion of the combustion chamber forming a variablevolume combustion chamber opening into the output when the valve discmoves towards the second axial end portion of the combustion chamber,wherein the multifunction valve comprises at least one duct having anoutput in the valve disc, the multifunction valve being arranged tosupply air, water or steam through said duct and supply said air, wateror steam from said output in the valve disc.
 2. A combustion chamberarrangement as claimed in claim 1, wherein the multifunction valve isoperated with an electric linear drive acting on the stem of themultifunction valve.
 3. A combustion chamber arrangement as claimed inclaim 2, wherein the electric linear drive is used as a generator togenerate electricity when the valve disc and the stem are moved by theexpansion of the ignited mixture of air and fuel in the first portion ofthe combustion chamber.
 4. A combustion chamber arrangement as claimedin claim 1, wherein the multifunction valve comprises at least one ductwithin the valve disc and is arranged to be cooled with water flowthrough said duct.
 5. A combustion chamber arrangement as claimed inclaim 1, wherein the multifunction valve comprises at least one ducthaving an output in the valve disc, the multifunction valve beingarranged to supply water through said duct and spray the water from saidoutput.
 6. A combustion chamber arrangement as claimed in claim 1,wehrein the multifunction valve is arranged to compress the inputcontents of the combustion chamber by reducing the volume of the firstchamber portion of the combustion chamber when fuel and air have beensupplied to the first chamber portion and the input valve is closed. 7.A power generating system having a turbine operably connected to one ormore compressors for converting energy fed to the turbine intomechanical energy of a rotatable power shaft and to compress air withone or more compressors. a combustion chamber arranged to receive fuelfrom a fuel tank and compressed air to initiate a combustion process andoutput combustion products into the turbine for rotating the rotor ofthe turbine and thereby rotating the power shaft, and an input valvefunctionally connected to the combustion chamber for controlling thecombustion process, which is a cycle process comprising a compressionphase and an expansion phase, one or more controllable input valves forproviding the compressed air to the combustion chamber, and a controlunit for controlling said one or more input valves, wherein the systemcomprises the combustion chamber arrangement of claim
 1. 8. A powergenerating system as claimed in claim 7, wherein the system furthercomprises an air chamber for heating air inside the air chamber, whereinthe air chamber is arranged to receive compressed air from the one ormore compressors, heat the compressed air and exhaust the heatedcompressed air to the combustion chamber.
 9. A power generating systemas claimed in claim 8, wherein the air chamber is cooled with a fluid.10. A power generating system as claimed in claim 8, wherein the airchamber further comprises one or more air ducts within the air chamberfor flowing ambient or heated air in order to heat or cool the airinside the air chamber.
 11. A power generating system as claimed inclaim 7, wherein the system further comprises: a heat exchanger inthermal interaction with the combustion products exhaust from theturbine for transferring heat from the exhaust combustion products intosteam, one or more input valves for providing the steam to the turbine,and a control unit for controlling said one or more input valves forgenerating a time-dependent steam injection into the turbine.
 12. Apower generating system as claimed in claim 11, wherein the systemfurther comprises: a steam tank for accumulating steam, a condenser forcondensing the steam into water, a water tank (36) for accumulating thewater, where water is pumped from the water tank to the heat exchangerto vaporize the water into steam which is arranged to flow into thesteam tank.
 13. A power generating system as claimed in claims 7,wherein the combustion chamber is arranged to work in cycles.
 14. Apower generating system as claimed in claim 13, wherein the combustionchamber is arranged to work in two alternating cycles wherein the firstcycle is a combustion cycle in which fuel is fed to the combustionchamber and the second cycle is a cooling cycle in which a fluid isarranged to flow through the combustion chamber for cooling thecombustion chamber.
 15. The power generating system of claim 7 whereinthe multifunction valve is operated with an electric linear drive actingon the stem of the multifunction valve.
 16. The power generating systemof claim 15 wherein the electric linear drive is used as a generator togenerate electricity when the valve disc and the stem are moved by theexpansion of the ignited mixture of air and fuel in the first portion ofthe combustion chamber.
 17. The power generating system of claim 7wherein the multifunction valve comprises at least one duct within thevalve disc and is arranged to be cooled with water flow through saidduct.
 18. The power generating system of claim 7 wherein themultifunction valve comprises at least one duct having an output in thevalve disc, the multifunction valve being arranged to supply waterthrough said duct and spray the water from said output.
 19. The powergenerating station of claim 7 wherein the multifunction valve isarranged to compress the input contents of the combustion chamber byreducing the volume of the first chamber portion of the combustionchamber when fuel and air have been supplied to the first chamberportion and the input valve is closed.